Ok so you have two bins joined by a tube. That is ok if one of the bins is bigger. Two smaller ones doesn't work the same as one larger one. If you have one larger one, it's fine to have a smaller one attached - although really they do better with just one larger one and they can then use different areas for different things.
So if you were thinking of upgrading her then one large bin would be better. Or - if you have space - a detolf. Which is a cheap ish option for a tank style cage. They can actually look really nice in a room as well if they are standing on ikea kallax units - and provide storage underneath. So that might be an option.
If you google "Hamster Detolf" and click on Images - you'll see a few examples
In that you have room for a deep digging end full of substrate, plus everything else and the hamster has a habitat with different areas to do different things in.
It's just an Ikea glass detolf cabinet on its side with the door left off, but it needs two lids making out of strips of wood with mesh attached.